Flower manipulation 27 th May 2015 Brief overview of project Brief discussion about understanding of flowering in mango and manipulation tools Presentation of ethephon and KNO 3 trials 2014/15 Proposed next steps

Short term Optimisation of existing chemicals KNO 3 Ethephon Paclobutrazol Better use of weather data Medium term New genetics NMBP New chemicals Longer term New tools

Bud age: 90 days. Preferentially second flush buds leaves recurved Aspect “stand by”, grayish leaf color, aspect crunchy Low nitrogen content: 1.0 – 1.3% Plant condition for floral induction (Brazil)

Phenological cycle 0 50 DAYS END OF HARVEST DAYS HARVEST Fruit weight - g PRUNING ANDFERTILIZATIONSTART FLUSHINGCULTARGROWTH STOPPED - ETHEPHONBeginning floral induction Floral induction FinishedFlowering startsFull flowering FLOWERING FINISHED FIRST FRUIT ABORTIONSECOND FRUIT ABORTION Growth curve of fruits. K2OK2O linha da NIL COEFICIENT - Kc POTENTIAL EVAPOTRANSPIRATION – ETp 1,00 0,90 0,80 0,70 0,60 0,50 0,40 0,30 0,20 0,10 0,00 VEGETATIVE PHASE / FLUSH MATURATION WATER STRESS DORMENCY (RETORNO) 2nd Fruit Abortion FRUIT GROWTH Fruit induction HARVEST

What assists Mango flowering Mature leaves, recurved, hard green, crunchie Cool weather (<20 o C) Growth (At the right time) Paclobutrazol (Cultar® Payback ®) Ethephon (Ethrel ® Galleon ®) KNO 3 (Nitrate) Cincturing (Potentially Destructive) Low leaf N levels (<?)

Delaying growth using ethephon Use ethephon to prevent vegetative growth after the wet Use ethephon to hold a second vegetative flush after the wet Use ethephon to spread flower initiation both on an individual farm or within a district

Properties of Ethephon Label; temperature >18 o C and <32 o C Many crops use non-ionic wetters Store product in Cool location(4 o C vs 45 o C) DO NOT apply to weak or stressed plants. DO NOT apply if rain is expected within 8 hours of application. DO NOT mix with hard (alkaline) water.

Ethephon Registration application prepared by AMIA Permit granted Needs follow up research for final registration

Why are we spraying at night? Low temperatures Less wind Slower drying but Stomata closed Darwin weather

Treatments Spray 8/05/2014 Treatment 1 Water plus LI700 1ml/l Treatment 2290 g ai/ha (0.67 ml/L) ethephon plus 1ml/l LI700 Treatment 3580 g ai/ha (1.34 ml/L) ethephon plus 1ml/l LI700 Treatment 4870 g ai/ha (2.01 ml/L) ethephon plus 1ml/l LI700 Treatment 5 3% KNO 3 plus 1ml/l LI700 Spray 21/05/2014 Repeat Spray 10/06/2014 “Turned irrigation on” 12 trees of 25 with 3% KNO3 plus 1ml/l LI700 Spray 12/06/ 2014 Same 12 trees of 25 with 1.5% KNO3 plus 1ml/l LI700

Flowering Date Predicted Harvest date 10-May29- Aug 20-May9- Sep 30 - May19- Sep 1-Jun20-Sep 5-Jun24-Sep 10-Jun29-Sep 15-Jun4-Oct 20-Jun7-Oct 25-Jun12-Oct 30-Jun16-Oct 5-Jul20-Oct 10-Jul24-Oct 15-Jul28-Oct 20-Jul1-Nov 30-Jul9-Nov

Importance of South Easterlies

Darwin Temperatures ( o C) 2014

Sprayed with 3% KNO 3 10/6/2014 and 1.5% KNO 3 on 12/6/2014

Stage 1 Stage 2

Stage 3 Stage 4

Stage 5

TreatmentFlowering EastFlowering West Water0.0 KNO Ethephon Ethephon Ethephon Response 10 th June 2014

Plus KNO 3 Minus KNO 3 SideWestEastWestEast Water KNO Ethephon Ethephon Ethephon Response 10 th August 2014

Flush stage Treatment12345 waterOK 290 g ai/haX?XXXOK 580 g ai/haX?XXXOK 870 g ai/haX?XXXX 1160 g ai/haXX (X) X Observations Variable response on buds, killed outer scale leaves Highest dose killed shoots Highest dose effected light green fully expanded leaves

High dose killed shoots Defoliated shoots

2015 trials 18 th March Control (Bugmaster) 1% K 2 SO 4 Ethephon 580g ai/ha, plus LI th April Ethephon 960g ai/ha plus LI % KNO 3 (5 rows) plus LI700 21st May 2.5% KNO 3 (The farm) plus LI700

March April May

B74

Next steps Describe ethephon effects on leaves Review Paclobutrazol use. Investigate factors affecting KNO 3 uptake. Formulation, Boron and Zinc, Wetters, time of day, concentration, leaf age as part of bigger N program Assess the role of K 2 SO 4 on flush development